Method for treating and impregnating glass fiber bundles for reinforcement of elastomeric materials and product

ABSTRACT

The concepts of this invention reside in the coating of individual glass fibers, in connection with the glass fiberforming operation, with an elastomeric compatible composition having a curable elastomeric material, followed by at least partial cure of the elastomeric material before the bundle formed of a multiplicity of such coated glass fibers are flexed during processing of the glass fibers in strand, yarn, cord, or fabric formation, whereby the elastomeric-based composition is capable, even when present in an amount as low as 1-4 percent by weight solids, of protecting the coated glass fibers from breaking through the coating during flexure and whereby the bundle formed of the coated glass fibers can be processed to the form desired for use as a reinforcement without seizure or otherwise interfering with the processing steps, after which the bundle is impregnated with an elastomeric-based material for the desirable full loading of the glass fiber bundle to enhance the integration of the reinforcing bundle of glass fibers with the elastomeric matrix in the manufacture of glass fiber-reinforced elastomeric products.

United States Patent inventors Appl. No. Filed Patented Assignee METHODFOR TREATING AND IMPREGNATING GLASS FIBER BUNDLES FOR REINFORCEMENT OFELASTOMERIC MATERIALS AND PRODUCT 18 Claims, 4 Drawing Figs.

US. Cl 65/3, 117/72,!17/126GR ht. (I C03c 25/02 Field of Search 65/3;

117/72, 76 T, 126 GB, 126 GS I 56] References Cited UNITED STATESPATENTS 3.424,608 l/l969 MalachiQIQLTIIIIII 117/126 x PrimaryExaminer-William D. Martin Assistant ExaminerDavid CohenAttorneys-Staelin & Overman and Herman I. Hersh ABSTRACT: The conceptsof this invention reside in the coatmg of lndividual glass fibers, inconnection with the glass fiberforming operation, with an elastomericcompatible composition having a curable elastomeric material, followedby at least partial cure of the elastomeric material before the bundleformed of a multiplicity of such coated glass fibers are flexed duringprocessing of the glass fibers in strand, yarn, cord, or fabricformation, whereby the elastomeric-based composition is capable, evenwhen present in an amount as low as 1-4 percent by weight solids, ofprotecting the coated glass fibers from breaking through the coatingduring flexure and whereby the bundle formed of the coated glass fiberscan be processed to the form desired for use as a reinforcement withoutseizure or otherwise interfering with the processing steps, after whichthe bundle is impregnated with an elastomen'c-based material for thedesirable full loading of the glass fiber bundle to enhance theintegration of the reinforcing bundle of glass fibers with theelastomeric matrix in the manufacture of glass fiber-reinforcedelastomeric products.

METHOD F OR TREATING AND IMPREGNATING GLASS FIBER BUNDLES FORREINFORCEMENT 01F ELASTOMERIC MATERIALS AND PRODUCT This inventionrelates to the treatment of glass fibers for use a of the glass fibersin combination with elastomeric materials in the manufacture of glassfiber-reinforced elastomeric products, such as rubber belts, rubbertires and the like, fonned of natural or synthetic rubbers where highstrength, toughness and dimensional stability can be greatly benefittedby the presence of the glass fibers.

Considerable research and development have been, conducted inutilization of glass fibers as a reinforcement for elastomeric materialsin the manufacture of glass fiber-reinforced products.

From the careful analysis of such research and development, conductedover the past several years, it has been concluded that best use ofglass fibers as a reinforcement for elastomeric materials is achievedwhen the glass fibers are embodied in the elastomeric materials in theform of bundles of a multiplicity of glass fibers wherein the bundle iscapable of reacting as a unit with sufficient adjustment between thefibers to enable substantially all of the fibers in the bundle tocontribute their fair share in resisting the forces to which thereinforced product is being subjected.

Having established the basic requirements for a suitable glass fiberreinforcement for elastomeric products, the problem arises with respectto the method and means for producing glass fiber-reinforcing elementswhich meetthese basic requirements for their utilization as a glassfiber reinforcement in glass fiber-reinforced elastomeric products.

It is an object of this invention to produce and to provide a method forproducing reinforcing bundles of glass fibers in which the bundles ofglass fibers embody an elastomeric compatible material which provides aprotective coating on the individual glass fibers in the bundle and yetprevents interfilament bonding, which enables the fibers and the bundlesformed thereof to be flexed in processing to the desired arrangement forreinforcement without permitting the individual glass fibers in thebundle to cut through the protective coating, yet permits the glassfibers to be processed to the desired form for reinforcement, and whichembodies a full complement of elastomeric compatible material sufficientto achieve a strong and permanent interbonded relationship between thereinforcing bundle of glass fibers and the continuous phase elastomer inthe glass fiber-reinforced elastomeric product.

These and other objects and advantages of the invention will hereinafterappear and for purposes of illustration, but not of limitation, anembodiment of the invention is shown in the accompanying drawing inwhich H6. 1 is a schematic elevational view of one phase of the processfor coating the glass fibers in forming;

FIG. 2 is a partial sectional view of the bundle of glass fibersproduced by the phase of the operation shown in FIG. 1;

FIG. 3 is a schematic view of a further phase of the operation fortreatment of the glass fibers in accordance with the practice of thisinvention; and

FIG. 4 is a sectional view of a portion of a glass fiber bundle whichresults from the process illustrated in FIGS. 1-3.

In our copending application filed concurrently herewith and entitled"Method for Treating and lmpregnating Glass Fiber Bundles forReinforcement of Elastomeric Materials," description is made of onetechnique for preparation of a glass fiber reinforcement for elastomericproducts wherein the individual glass fibers are coated, during theglass fiber-forming operation, with an elastomeric compatiblecomposition in an amount sufficient to provide a protective coating onthe glass fiber surfaces to prevent the fibers from breaking through thecoating in response to flexure during processing of the glass fibers inbundle formation, i.e., the formation of the fibers into strands, yarn,cords or fabrics, and then impregnating the bundle of previously coatedfibers with additional elastomeric compah'ble composition to introduce afull complement of elastomeric compatible materials, defined as anamount sufi'icient to protect the fibers and to interbond the bundle ofcoated and impregnated glass fibers with a continuous phase ofelastomeric materials, while permitting adjustment between the glassfibers making up the bundle to enable the glass fibers to contributetheir fair share of reinforcement. Because of the tendency towardsseizure, the amount of elastomeric compatible material applied as acoating onto the glass fiber surfaces in forming was limited to from4-10 percent by weight, calculated on the dry solids basis andpreferably within the range of 7-8 percent by weight, while the amountadded by impregnation of the bundles fonned by the coated fibers wassufficient to bring the total loading of the glass fiber bundle to anamount greater than 10 percent by weight but less than 24 percent byweight, and preferably in an amount within the range of l4-20 percent byweight of elastomeric material, with best results being secured with anamount within the range of 16-18 percent by weight, calculated on a drysolids basis.

It has been found, in accordance with the practice of this invention,that less than 5 percent by weight to as little as l percent by weight(solids) of an elastomeric-based composition can be applied as a coatingonto the individual glass fiber filaments during the fiber-formingoperation, if the elastomeric material is subjected to at least partialcure, after and preferably before the multiplicity of the coated fibersare gathered together to fonn the strand, but before the strand isprocessed as by plying, twisting, intertwisting and/or waving intostrands, yarns, cords or fabrics. It is believed that when the coatingof elastomeric material is advanced to an intermediate or complete stageof cure, the coating is rendered sufficiently tough to preventbreakthrough of theglass fibers during fiexure of the glass fiberbundle, whereby the bundles of glass fibers can be processed asdescribed without deterioration of the fibers making up the reinforcedbundle.

Application of the elastomeric-based material in an amount less than 0.5percent by weight, on the dry solids basis, is insufficient to providethe desired protection to the glass fibers. In the preferred practice ofthis invention, it is desirable to coat the glass fibers in forming withthe curable elastomeric-based composition in coating weights within therange of 2-4 percent by weight of the coated fibers, when calculated onthe dry solids basis. When the glass fiber filaments are coated informing with an amount greater than 5 percent by weight of curableelastomeric-based material, the bundle of glass fibers subsequentlyformed is incapable of being penetrated sufficiently to enable thedesired subsequent impregnation with elastomeric-based materials, toachieve the additional loading believed to be desirable for thedevelopment of a good interbonded relationship between the glass fiberreinforcement and the continuous phase elastomer and to integrate theglass fiber reinforcement into the elastomeric product. When, on theother hand, the glass fibers are coated in forming with a curableelastomeric material in an amount less than 5 percent by weight, thebundle fonned with the at least partially cured elastomeric-basedmaterial coating the glass fibers is characterized by sufficientporosity to enable penetration of the glass fiber bundle byelastomeric-based impregnating compositions for the desired additionalloading of the glass fiber reinforcement. Introduction of additionalelastomeric-based material. by impregnation of the bundle of previouslycoated glass fibers, can be made by one or more impregnations tointroduce an amount of elastomeric-based material to bring the total ofelastomeric material in the glass fiber bundle to an amount grater than8 percent by weight of dry solids and preferably to an amount greaterthan 12 percent by weight. lt is undesirable to exceed an amount greaterthan 24 percent by weight elastomeric-based material by such subsequentimpregnation of the glass fiber bundle, since any such greater amountsof elastomeric material merely form into encapsulating rubber layerswhich are free of glass fibers and thus incapable of contributing to thereinforcement.

The curable elastomeric material can be applied, in fonning, -to coatthe individual glass fibers with an amount of elastomeric-based materialgreater than 5 percent by weight, but then it is desirable to apply thefull increment of elastomeric material in the forming step, sinceadditional elastomeric material introduced by impregnation merelyoperates to coat the bundle of glass fibers as distinguished from thedesired impregnation thereof. As a result, when the full increment ofelastomeric material is applied by coating the individual glass fibersduring the forming operation, it is desirable to apply the curableelastomeric material in coating weights which exceed 8 percent by weightof coated glass fibers and preferably in coating weights of 10-16percent by weight of the coated glass fibers. While such coated glassfibers are difficult to process into glass fiber bundles withoutseizure, in the absence of previous drying or cure, the glass fiberswith such amounts of rubber-based materials can be processed to the formdesired for reinforcement without seizure after the elastomeric materialhas been heated to cure or at least partial cure.

When the bundle of glass fibers contains the full complement ofelastomeric-based material in the cured or partially cured state, itbecomes difficult to integrate the reinforced bundles of glass fibersinto the continuous phase of elastomeric material in forming the glassfiber-reinforced elastomeric product. Nevertheless, a sufficientlystrong interbonded relationship can be established, preferably by theuse of interfacial bonding agents, such as organo-silicon compoundscontaining amino, epoxy or carboxylic groups. It is preferred, however,to make use of the system initially described wherein the glass fibersare coated in forming with an amount of curable elastomeric materialwithin the range of 0.5-5 percent by weight, whereby a porous bundle ofglass fibers is formed which is capable of being penetrated forsubsequent impregnation with elastomeric-based material to provide theadditional increment for full integration of the glass fiberreinforcement into the elastomeric product.

Under such circumstances, the glass fiber reinforcement comprises abundle of glass fibers in which the individual glass fibers in thebundle are coated with elastomeric-based material throughout the crosssection of the glass fiber bundle, with the concentration of theelastomeric material in the glass fiber bundle increasing from thecenter of the bundle outwardly and preferably with a layer ofelastomeric material encompassing the impregnated bundle of coated glassfibers. A reinforced bundle of the type described is capable ofproviding protection for the individual glass fibers to prevent theirbreaking through the coating during fiexure of the glass fiber bundlewhile also permitting interbonding between the reinforcing bundle of theglass fibers and the elastomeric matrix forming the continuous phaseduring vulcanizing or cure to form the glass fiber-reinforced product.

As used herein, the term elastomeric compatible material includesresinous-based and elastomer-based materials and the term"elastomeric-based material" is meant to refer to a glass fiber coatingcomposition or a glass fiber bundle impregnating composition in which anelastomeric material constitutes the sole solids component of thecoating or impregnating composition or preferably embodies a componentof the coating or impregnating composition in combination with othermaterials such as a resin, as represented by phenol formaldehyde resin,melamine fonnaldehyde resin, epoxy resin, polyester resin, resorcinolformaldehyde resin and the like, or a filler such as zinc oxide, carbonblack and the like, and/or a lubricant such as graphite, wax or thelike, or the combination of elastomers alone or in combination with theresinous material as represented by the compositions described in thecopending applications, Ser. No. 398,305, filed Sept. 22, I964; Ser. No.400,517, filed Sept. 30, 1964, now abandoned;

Ser. No. 397,956, filed Sept. 21, 1964 now U.S. Pat. No.

3,402,064, and Ser. No. 494,654, filed Oct. ll, I965, now abandoned. I

As used herein, the term continuous phase elastomer" is meant to referto the rubber or elastomeric phase fonning the continuous phase of theelastomeric product. The elastomeric phase of the coating compositionand/or the impregnating composition may be the same or different thanthe elastomeric material forming the continuous phase but it isdesirable that such elastomeric material be compatible one with theother, at least in their uncured state, so as to avoid phase separation.

The composition applied to the glass fiber surfaces in forming shouldcontain a rubber component which is curable and which becomes stronglybonded to the glass fiber surfaces upon cure or partial cure, with orwithout an anchoring agent present, such as an organo-silicon compoundcontaining amino, epoxy or carboxy groups, as represented by agammaaminopropyltriethoxysilane. As the rubber elastomeric component inthe coating, use can be made of natural rubber formulated into a sizecomposition with usual accelerators, catalysts and promoters for sulfurcure, or use can be made of butadiene rubbers, and rubbers fonned ofbutadiene copolymerized with a monoolefin such as styrene, nitriles,acrylic acids and esters thereof and terpolymers of butadiene withstyrene, acrylonitrile and vinyl pyridine. The aforementioned rubbersare curable in the presence of heat and/or catalyst and such curablerubbers also include carboxylated modified derivatives of such butadienerubbers as represented by carboxylated butadiene-styrene copolymer,carboxylated butadiene acrylonitrile, carboxylatedbutadiene-styrene-vinyl pyridine copolymer and carboxylatedbutadiene-styreneacrylonitrile terpolymer. Use may also be made of othersulfur curing or free radical curing rubbers, such as the EPDM rubbers.Such elastomeric components are preferably formulated in the sizecomposition with adhesion-promoting resinous systems, such as resorcinolformaldehyde resins.

As the elastomeric material of the continuous phase and of theimpregnating compositions, use can be made of natural rubber or asynthetic rubber, such as fonned by polymerization of monomericmaterials such as chloroprene, various of the conjugated butadienes,such as l,3-butadiene, methyl-2- butadiene, l,3-piperylene, and2,3-dimethyl butadiene; and mixtures of such conjugated butadienes withother copolymerizable monomers, such as up to 50 percent or more byweight of a monomer which contains a monoolefinic group. such as arylolefins, as represented by styrene and vinyl naphthalene; andalpha-methylene carboxylic acids and their corresponding esters, nitrilsand amides, such as acrylic acid, methyl acrylates, methylmethacrylate,acrylonitrile, methylacrylamine and the like; isobutylene,methyl-vinyl-ester and methyl-vinyl-ketone. The elastomeric componentmay also comprise an EPDM-type rubber such as formed by theinterpolymerization of ethylene, monoolefin containing from three to l 8carbon atoms, such as propylene, butylene, etc, and a polyolefin, suchas cyclopentadiene, l,2-hexadiene, and preferably a5-alkenyl-2-norbornene or a 5-alkylidene-2-norbomene, such as5-ethylidene-2-norbomene, S-propylidene- 2-norbomene,S-butenyl-Z-norbomene, and the like.

As used herein, the tenn "coating the glass fiber filaments duringforming" is meant to refer to a coating of the individual glass fibersas they are drawn by rapid attenuation of molten streams of glassissuing from openings through the wall of a bushing or feedercommunicating with a glass-melting chamber. The attenuated glass fibersare gathered together to form a strand which is suitably collected, asby being wound upon a rapidly rotating drum or spindle. Some hundreds ofsuch glass fiber filaments are gathered together to form the strandwhich can be later plied, twisted or intertwisted with outer strands toform yarns or cords, which can be processed by weaving or the like intodesired reinforcing fabrics. Application of the elastomeric-basedcoating composition is made in the conventional manner by a pad orroller continuously wet with the composition and over which thefilaments are drawn as they are gathered together to form the bundle.This describes the forming operation for continuous fibers. Withdiscontinuous fibers, formed by engaging the molten streams of glasswith downwardly directed blasts of high-pressure air, steam or gas,treating composition may be sprayed onto the discontinuous fibers asthey rain down onto a collecting surface, either gravitationally or withthe aid of the blast. Instead, the treating composition can be appliedafter the discontinu ous fibers have been collected on the surface butbefore removal for drafting to form the yarn.

Specific description will now be made of the practice of this inventionwith the following glass fiber treating and impregnating compositionsset forth by way of examples:

EXAMPLE l 5% by weight carboxylato butadiene-styrene (7i butadiene,

29 styrene) 0.2% by weight gamma-aminopropyltriethoxysilane 0.2% byweight surface active agent 94.6% by weight water EXAMPLE 2 4% by weightbutadiene-styrene copolymer'(70-30) 0.5% by weight surface active agent95.5% by weight water EXAMPLE 3 3% by weight butadiene (70)-styrene 15)-vinyl pyridine l5)terpolymer 0.5% by weight surface active agent 96.5%by weight water EXAMPLE 4 W parts by weight natural rubber latex (40%rubber) l .0 pans by weight stearic acid 1.5 parts by weight mercaptobenzothiazole 3.0 parts by weight tetramethyl thiuram monosulfide l.0part by weight sulfur EXAMPLES 5% by weight carboxylatobutadiene-acrylonitrile copolymer (60:40)

0.4% surface active agent 94.6% by weight water EXAMPLE 6 6% by weightbutadiene-styrene-acrylonitrile terpolymer 1% by weight emulsify ngagent 93% by weight water EXAMPLE 7 5% by weight butadiene (70)-styrene(30) copolymer 3% by weight resorcinol formaldehyde-latex resin (Lotol5440) 0.5% weight surface active agent 91.5% by weight water EXAMPLE 8strand 18 after they are brought together over a guide 22, with thestrand being wound about a rapidly rotating drum 20.

Application of the coating composition of example 1-8 is made to theindividual glass fiber filaments it) before they are gathered togetheras by means of a roller 24 so that the individual fibers or filamentswill each be individually coated with a layer of the coatingcomposition. The peripheral surface of the roller is continuously wet byan applicator blade or brush with material fed from a reservoir 26 andthe individual filaments ride over the periphery of the rollersubsequent to their attenuation, but before they are gathered togetherto form the bundle. After being coated by the roller, the guide pad 22can be used to gather the fibers together to form the bundle in whichthe individual fibers l0 are wet with the coating composition. More thanone applicator roller may be employed for wetting the individual glassfibers, depending somewhat upon the solids content of the coatingcomposition and the amount that is picked up 'by' the fibers. Howeverperfon-ned, application of coating composition to the individual glassfibers should provide a coating having a dry coating weight of less than5 percent and preferably within the range of l-3 percent by weight baseduponthe coated glass fibers.

Before the fibers are gathered together to form the strand, the coatedfibers are flash heated, as by means of highfrequency heating means 26to heat the coating to a temperature within the range of 350-600 F.;'and preferably to a temperature within the range of 400450 F., for atime sufficient to flash off the water and advance the elastomericcomponent to a partially curedstage. A fraction of a second up to a fewseconds is sufficient to effect the desired cure. In order to providefor the length of heating, the high-frequency means may comprise atubular high-frequency cell through which the fibers are advanced or aseries of platesforming poles for inducing'the high-frequency currentfor heat generation into the coating during passage from the applicatorroll to the collecting guide.

The formed strands of glass fibers 18 can be combined with otherstrands,'-or plied, twisted or otherwise interlaced with other strandsto form threads, yarns or cords which can be -further processed byweaving to form woven or nonwoven fabrics or -cut or chopped to shortlengths such as l to 3 inches, all of which are included herein withinthe term "glass fiber bundle" to define the product which is subjectedto the subsequent impregnation operation to incorporate the additionalamounts of rubber-based material adapted at least partially to penetrateinto the treated glass fiber bundle and to build up the higherconcentration of rubber in the outer portions of the glass fiber bundle,by comparison with the interior ofthe coated bundle of glass fibers.

-After processing the coated and partially cured glass fibers to thedesired-bundle form for combination with the continuous phase elastomcrin the manufacture of glass fiber-reinforced elastomeric products, thebundles of glass fibers are immersed or otherwise wet with arubber-based impregnating composition as hereinafter described. Thestrand of glass fibers can be advanced by a pulling wheel which drivesthe strand to a talteup device provided with a magnetic clutch or into abox or other suitable collecting device.

lmpregnating Compositions as described in application,=Ser. No. 398,305;

EXAMPLE 9 60% by weight natural rubber latexresorcinol formaldehyderesin dispersed in aqueous medium to 38% solids (Lotol 5440-U.S. RubberCompany) 40% by weightwater EXAMPLE l0 l5% weight natural rubberlatex-resorcinol formaldehyde resin dispersed in aqueous medium to 38%solids 82% by weight water 3% by weight gamma-aminopropyltriethoxysilaneThe dispersion and water mixture are made alkaline with quaternaryammonium hydroxide before addition of the silane. ImpregnatingCompositions as described in application, Ser. No. 400,5 l7:

EXAMPLE I l 2.0 parts by weight resorcinol formaldehyde resin l.4 partsby weight fonnaldehyde 5.0 parts by weight concentrated ammoniumhydroxide 25.0 parts by weight vinyl pyridine-butadiene-styreneterpolymer in the ration of 15:70: 1 5- 4 l solids (Gen-Tac FS-GeneralTire and Rubber Co.) 1 50.0 parts by weight neoprene rubber latex (50%solids) 7.4 parts by weight butadiene-latex (60% solids) 0.2 part byweight sodium hydroxide 58.0 parts by weight water EXAMPLE l2 2.0 partsby weight resorcinol formaldehyde resin l.0 part by weight formaldehyde(37% solution) 2.7 parts by weight concentrated ammonium hydroxide 25.0parts by weight vinyl pyridine-butadiene-styrene terpolymer latex (42%solid) 4i .0 parts by weight neoprene rubber latex (50% solids) 5.0parts by weight butadiene latex (60% solids) 0.05 parts by weight sodiumhydroxide l.0 part by weight gamma-aminopropyltriethoxysilane l, l partsby weight water lmpregnating Compositions as described in application,Ser. No. 494,654;

EXAMPLE 13 220 parts by weight water I part by weight sodium hydroxide22 parts by weight resorcinol formaldehyde resin (70% solids) 15 partsby weight Formalin 30 parts by weight ammonium hydroxide 250 parts byweight vinyl pyridine-butadiene-styrene terpolymer latex l5:70:l5) (41%solids) 415 parts by weight neoprene rubber latex (50% solids) 5l partsby weight butadiene rubber latex (60% solids) 1 l5 parts by weightcarbon black For a schematic illustration, but not by way of limitation,a cord 40 of coated glass fibers in bundle form is advanced continuouslyover roller 42 for passage downwardly under rollers 44 and 46 andupwardly through a die 48 for complete immersion in a bath 50 of theimpregnating composition, as described in examples 9- l 3. Duringpassage through the bath, the bundle of coated glass fibers will beimpregnated with the composition to increase the amount of rubber solidsembodied within the glass fiber bundle.

Although the rubber of the coating initially applied to the glass fibersof the bundle is at least partially cured, the amount of rubber appliedas a coating is insufiicient completely to fill the interstices betweenthe fibers of the bundle or to block penetration of the bundle by thesubsequently applied impregnating composition. Thus the impregnatingcomposition will penetrate towards the interior of the bundle but mostof the composition will be retained in the outer portions of the bundlewhereby the concentration of impregnating solids will be greater in theouter portions of the bundle than in the interror.

The bundle may be passed through the bath one or more times, preferablywith intermediate drying, until the total amount of rubber-basedtreating composition, calculated on the solids basis, adds up to morethan 10 percent and preferably within the range of l2-18 percent byweight of the treated glass fiber system.

As the impregnated bundle of glass fibers works through the die 48, theimpregnating composition will be forced into the interior of the bundlewhile excess will be wiped from the outside thereof. Other auxiliarymeans may be employed to enhance impregnation, such as flexure of thebundle during impregnation to open the bundle, or by the use ofalternating pressure impulses and the like for working the compositioninto the bundle.

The impregnated bundle of glass fibers is dried. preferably by exposureto elevated temperature, such as temperature within the range of 250-500F. for a short period of time to remove the volatiles and preferably fora period of time partially to advance the elastomeric material of theimpregnating composition to a partially cured stage. Exposure for a timeand a temperature to effect full cure or vulcanization of theelastomeric material should be avoided, otherwise proper in tegration ofthe treated glass fiber bundle with the continuous phase elastomer willbe diflicult to achieve during normal pressure molding or vulcanizationsteps used in the manufacture of the reinforced elastomeric product.

The results of the impregnation is a glass fiber bundle havingelastomeric-based material distributed throughout the cross section ofthe glass fiber bundle, with the individual glass fibers coated with theelastomeric-based material advanced to partially cured stage, but inwhich the distribution of elastomeric material throughout the bundleranges from a central portion in which the elastomeric material ispresent primarily in the form of the elastomeric coating applied to theglass fibers, an intermediate portion which comprises the combination ofthe elastomeric coating material supplemented by the elastomericimpregnating material, and outer portions comprising the coating appliedto the individual glass fibers but in which the elastomeric component isdominated by the portion introduced as the impregnating composition,with possibly possibly layer of the latter encasing the impregnatedbundle.

In effect, the original treatment of the glass fibers to coat theindividual glass fibers in forming produces a relatively porous bundleof glass fibers which permits penetration of the impregnatingcomposition for anchorage, yet provides a tough coating on the glassfiber surfaces which operates to protect the individual glass fibersfrom destruction by mutual abrasion during flexing of the glass fiberbundle in strand, yarn. cord, or fabric formation. The initial treatmentto coat the individual glass fibers with the partially cured elastomericmaterial also provides insurance for the presence of rubber-basedmaterial throughout the cross section of the glass fiber bundle whilepermitting rubber-based impregnating composition to be received withinthe bundle to effect the desired interconnection between the glassfibers making up the bundle and the continuous phase elastomer, therebyto maximize the contribution of the glass fibers as a reinforcement ofelastomeric products.

With this construction, maximum utilization can be made of the glassfiber system as a reinforcement for the continuous phase elastomer andfor maximizing the contribution of the high-strength properties of theglass fibers, without the need to rely upon the use of an anchoringagent to effect the desired interbonded relationship between the glassfibers and the elastomeric material. The presence of rubber-basedcoating and impregnating compositions about the glass fiber filamentsand through the cross section of the glass fiber bundle operates tointegrate the glass fiber system into the continuous phase elastomerwhile still permitting relative movement between the individual fibersmaking up the bundle for realignment of the fibers in direction offorce.

it will be apparent from the foregoing that we have provided a new andimproved concept in the pretreatment of glass fibers and bundles formedthereof whereby the fibers can be processed to the desired condition foruse as a reinforcement while incorporating the desired complement ofelastomeric material for physical engagement between the entire bundleof glass fibers and the continuous phase elastomeric material whilepermitting readjustment of the individual glass fibers.

It will be understood that changes may be made in the details offormulation and application without departing from the spirit of theinvention, especially as defined in the following claims.

We claim:

1. In the preparation of a reinforcement for glass fiberelastomericproducts in which the elastomeric material constitutes a continuousphase with the glass fibers arranged therein in bundles formed of amultiplicity of glass fibers, the steps of preparation of the glassfibers in the bundle form with an elastomeric based material loading ofmore than 10 percent and less than 24 percent by weight on the drysolids basis, comprising the steps of coating the individual glassfibers prior to bundle formation with a composition containing a curableor a vulcanizable elastomeric component in a coating weight within therange of 0.5- percent by weight of coated fibers, advancing theelastomeric component to at least a partially cured or vulcanized state,forming the multiplicity of coated glass fibers into glass fiberbundles, and then impregnating the rocessed bundle of glass fibers,prior to their combination with the continuous phase elastomer, with arubber-based impregnating composition to load the glass fiber bundleswith more than percent by weight dry solids of elastomeric basedmaterial.

2. The process as claimed in claim 1 in which the elastomeric materialin the coating is advanced by heating the coated glass fibers.

3. The process as claimed in claim 2 in which the coated glass fibersare heated to a temperature within the range of 350-600 F.

4. The process as claimed in claim 1 in which the elastomeric-basedcoating composition and the elastomeric-based impregnating compositionare substantially the same.

5. The process as claimed in claim 1 in which the amount of coatingapplied to the individual glass fibers is within the range of 2-4percent by weight on the dry solids basis.

6. The process as claimed in claim 1 in which the elastomeric coating isapplied to the glass fibers in forming to coat the individual glassfibers.

7. The process as claimed in claim 1 in which the totalelastomeric-based material in the impregnated bundles of glass fibers iswithin the range of l0-l8 percent by weight of the impregnated glassfiber system.

8. The process as claimed in claim 1 which includes the steps ofcombining the impregnated bundle of glass fibers with the continuousphase elastomer and molding the glass fiberelastomeric producttherefrom.

9. The process as claimed in claim 1 in which the glass fiber bundle hasrubber-based material distributed substantially throughout the bundle ofglass fibers with a higher concentration of elastomeric-based materialat the outer portions of the glass fiber bundle by comparison with theinterior and with the elastomeric material coating each of the fibers inan advanced state of cure or vulcanization.

10. The process as claimed in claim 9 in which the bundle issubstantially enclosed within a layer of the elastomeric-based material.

1 1. In the preparation of an element of glass fibers for use in thereinforcement of elastomeric materials forming the continuous phase inthe manufacture of glass fiber elastomeric products, the method forimproving the integration of the glass fiber component with theelastomeric material comprising the steps of providing a glass melt,issuing a plurality of streams of molten glass from the melt, rapidlyattenuating the streams of molten glass into fine flexible glass fibers,coating the individual glass fibers immediately afier forming with acomposition containing a curable or vulcanizable elastomeric material inan amount up to 5 percent by weight but more than 0.5 percent by weight,calculated on the dry solids basis, gathering the coated fibers into aglass fiber bundle, heating the fibers before or alter bundle formationto advance the elastomeric component to at least a partially cured orvulcanized state, processing bundles of such coated glass fibers to thefonn desired for combination with the continuous hase elastomer, andimpregnating the processed bundles 0 glass fibers with a rubber-basedimpregnating composition to provide a total loading of coating andimpregnating composition of more than 10 percent but less than 18percent by weight calculated on the dry solids basis.

12. The method as claimed in claim 11 in which the amount of coatingapplied to the glass fibers is within the range of 2-4 percent by weightsolids.

13. In the method of producing glass fiber-reinforced elastomericproducts comprising combining the elastomeric material forming thecontinuous phase in the elastomeric product in an uncured orunvulcanized state with glass fibers in bundle form loaded with morethan 10 percent by weight but less than 18 percent by weight ofelastomeric based material with with individual fibers coated with 0.5-5percent by weight of an elastomeric material in at least a partiallycured or vulcanized state, molding the combination of glass fiberbundles and continuous phase elastomer and advancing the elastomericmaterial to a set stage.

14. The method as claimed in claim 13 in which the glass fiber bundlesare loaded with the elastomeric based material in an amount within therange of 10-18 percent by weight.

15. The method as claimed in claim l3 in which the molded elastomericmaterial and glass fiber product are advanced to a cured stage.

16. The method as claimed in claim 13 in which the molded elastomericmaterial and glass fiber product are advanced to a vulcanized stage.

17. A bundle formed of a multiplicity of glass fibers, an elastomericbased material distributed throughout the cross section of the glassfiber bundle with the concentration of elastomeric-based material beinghigher in the outer portions of the glass fiber bundle than in thecentral interior portion of the glass fiber bundle with the individualfibers coated with 0.5-5 percent by weight of an elastomeric material inat least a partially cured or vulcanized state and with the amount ofloading of the elastomeric based materials in the glass fiber bundlesbeing within the range of 10-24 percent by weight.

18. A glass fiber reinforcement for elastomeric materials comprising abundle formed of a multiplicity of glass fibers in which the individualglass fibers of the bundle have a coating of elastomeric-based materialin at least a partially cured or vulcanized state and in which thebundle of glass fibers is fully loaded with elastomeric-based materialin an amount sufficient to interbound the bundle with the continuousphase elastomer to be reinforced while protecting the individual glassfibers in the bundle to prevent the fibers from breaking through duringflexure and wherein the individual glass fibers in the bundle arecapable of relative movement sufficient to contribute theirproportionate share of reinforcement in the bundle.

1 i i i t

2. The process as claimed in claim 1 in which the elastomeric materialin the coating is advanced by heating the coated glass fibers.
 3. Theprocess as claimed in claim 2 in which the coated glass fibers areheated to a temperature within the range of 350*-600* F.
 4. The processas claimed in claim 1 in which the elastomeric-based coating compositionand the elastomeric-based impregnating composition are substantially thesame.
 5. The process as claimed in claim 1 in which the amount ofcoating applied to the individual glass fibers is within the range of 2-4 percent by weight on the dry solids basis.
 6. The process as claimedin claim 1 in which the elastomeric coating is applied to the glassfibers in forming to coat the individual glass fibers.
 7. The process asclaimed in claim 1 in which the total elastomeric-based material in theimpregnated bundles of glass fibers is within the range of 10-18 percentby weight of the impregnated glass fiber system.
 8. The process asclaimed in claim 1 which includes the steps of combining the impregnatedbundle of glass fibers with the continuous phase elastomer and moldingthe glass fiber-elastomeric product therefrom.
 9. The process as claimedin claim 1 in which the glass fiber bundle has rubber-based materialdistributed substantially throughout the bundle of glass fibers with ahigher concentration of elastomeric-based material at the outer portionsof the glass fiber bundle by comparison with the interior and with theelastomeric material coating each of the fibers in an advanced state ofcure or vulcanization.
 10. The process as claimed in claim 9 in whichthe bundle is substantially enclosed within a layer of theelastomeric-based material.
 11. In the preparation of an element ofglass fibers for use in the reinforcement of elastomeric materialsforming the continuous phase in the manufacture of glass fiber -elastomeric products, the method for improving the integration of theglass fiber component with the elastomeric material comprising the stepsof providing a glass melt, issuing a plurality of streams of moltenglass from the melt, rapidly attenuating the streams of molten glassinto fine flexible glass fibers, coating the individual glass fibersimmediately after forming with a composition containing a curable orvulcanizable elastomeric material in an amount up to 5 percent by weightbut more than 0.5 percent by weight, calculated on the dry solids basis,gathering the coated fibers into a glass fiber bundle, heating thefibers before or after bundle formation to advance the elastomericcomponent to at least a partially cured or vulcanized state, processingbundles of such coated glass fibers to the form desired for combinationwith the continuous phase elastomer, and impregnating the processedbundles of glass fibers with a rubber-based impregnating composition toprovide a total loading of coating and impregnating composition of morethan 10 percent but less than 18 percent by weight calculated on the drysolids basis.
 12. The method as claimed in claim 11 in which the amountof coating applied to the glass fibers is within the range of 2-4percent by weight solids.
 13. In the method of producing glassfiber-reinforced elastomeric products comprising combining theelastomeric material forming the continuous phase in the elastomericproduct in an uncured or unvulcanized state with glass fibers in bundleform loaded with more than 10 percent by weight but less than 18 percentby weight of elastomeric based material with with individual fiberscoated with 0.5-5 percent by weight of an elastomeric material in atleast a partially cured or vulcanized state, molding the combination ofglass fiber bundles and continuous phase elastomer and advancing theelastomeric material to a set stage.
 14. The method as claimed in claim13 in which the glass fiber bundles are loaded with the elastomericbased material in an amount within the range of 10-18 percent by weight.15. The method as claimed in claim 13 in which the molded elastomericmaterial and glass fiber product are advanced to a cured stage.
 16. Themethod as claimed in claim 13 in which the molded elastomeric materialand glass fiber product are advanced to a vulcanized stage.
 17. A bundleformed of a multiplicity of glass fibers, an elastomeric based materialdistributed throughout the cross section of the glass fiber bundle withthe concentration of elastomeric-based material being higher in theouter portions of the glass fiber bundle than in the central interiorportion of the glass fiber bundle with the individual fibers coated with0.5-5 percent by weight of aN elastomeric material in at least apartially cured or vulcanized state and with the amount of loading ofthe elastomeric based materials in the glass fiber bundles being withinthe range of 10-24 percent by weight.
 18. A glass fiber reinforcementfor elastomeric materials comprising a bundle formed of a multiplicityof glass fibers in which the individual glass fibers of the bundle havea coating of elastomeric-based material in at least a partially cured orvulcanized state and in which the bundle of glass fibers is fully loadedwith elastomeric-based material in an amount sufficient to interboundthe bundle with the continuous phase elastomer to be reinforced whileprotecting the individual glass fibers in the bundle to prevent thefibers from breaking through during flexure and wherein the individualglass fibers in the bundle are capable of relative movement sufficientto contribute their proportionate share of reinforcement in the bundle.